This proposal is for examination of some of the critical factors involved in the production and maintenance of the obese state. Specifically, the interactions of adipose cellularity, food intake, diet, spontaneous and forced exercise, hyperinsulinemia, and tissue resistance of muscle and adipose tissue will be studied in genetically obese and force-fed laboratory rodents. Thus, the sequence of events and their relative importance in the production and maintenance of obesity will be elucidated. BIBLIOGRAPHIC REFERENCES: Johnson, P.R., J. S. Stern and J. Grinker. Patterns of activity and food intake in the genetically obese Zucker rat (fafa). In: Recent Advances and Obesity Reseach: I, Proceedings of First International Congress on Obesity, Alan Howard, Ed., Newman Publishing Ltd., p. 111, 1975. Stern, J.S., P. R. Johnson, B. R. Batchelor, L. M. Zucker and J. Hirsch. Pancreatic insulin release and peripheral tissue resistance in Zucker obese rats fed high and low carbohydrate diets. Am. J. Physiol. 228: 543 (1975).